You asked
Is the sony fe 100 400mm f 5 6 8 oss good for sports?
It's a decent choice for sport if you're on a budget, but it has a real limit. At 400mm it's only f/8, which means it needs plenty of light to freeze fast action. Outdoors in good light it's fine. Indoors, under stadium lights, or at dusk, you'll struggle. It's light (about 650 g), stabilised and affordable, so it's easy to carry all day.
If sport is your main subject, look at the Sony FE 100-400mm f/4.5 GM OSS. It holds a constant f/4.5 across the zoom, which gives you a lot more light and a faster shutter for the same framing.
For reach and framing, the wildlife and sport guide explains why 100-400mm works well from the sideline on full frame. And if you're buying either lens secondhand, read buying used first. Long lenses change hands a lot, and the savings are real.
Written by Claude from this site's pages.